From: Yonghong Song <yonghong.song@linux.dev>
To: Alan Maguire <alan.maguire@oracle.com>, andrii@kernel.org
Cc: ast@kernel.org, jolsa@kernel.org, daniel@iogearbox.net,
martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org,
john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me,
haoluo@google.com, nilay@linux.ibm.com, bvanassche@acm.org,
bpf@vger.kernel.org
Subject: Re: [PATCH bpf] libbpf: BTF dedup should ignore modifiers in type equivalence checks
Date: Fri, 9 Jan 2026 08:28:04 -0800 [thread overview]
Message-ID: <5eccbe20-7439-4c2d-a60d-bc0c11995207@linux.dev> (raw)
In-Reply-To: <20260109101325.47721-1-alan.maguire@oracle.com>
On 1/9/26 2:13 AM, Alan Maguire wrote:
> We see identical type problems in [1] as a result of an occasionally
> applied volatile modifier to kernel data structures. Such things can
> result from different header include patterns, explicit Makefile
> rules etc. As a result consider types with modifiers const, volatile
> and restrict as equivalent for dedup equivalence testing purposes.
>
> Type tag is excluded from modifier equivalence as it would be possible
> we would end up with the type without the type tag annotations in the
> final BTF, which could potentially lead to information loss.
>
> [1] https://lore.kernel.org/bpf/42a1b4b0-83d0-4dda-b1df-15a1b7c7638d@linux.ibm.com/
>
> Reported-by: Nilay Shroff <nilay@linux.ibm.com>
> Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Tested with llvm22 and gcc15 for config including CONFIG_DEBUG_INFO_BTF
and CONFIG_KCSAN. Both work properly.
Tested-by: Yonghong Song <yonghong.song@linux.dev>
next prev parent reply other threads:[~2026-01-09 16:28 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-09 10:13 [PATCH bpf] libbpf: BTF dedup should ignore modifiers in type equivalence checks Alan Maguire
2026-01-09 10:33 ` bot+bpf-ci
2026-01-09 12:24 ` Alan Maguire
2026-01-09 16:28 ` Yonghong Song [this message]
2026-01-09 17:28 ` Andrii Nakryiko
2026-01-10 14:05 ` Alan Maguire
2026-01-13 21:48 ` Andrii Nakryiko
2026-01-14 18:41 ` Alan Maguire
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